The West Wing actor lives close to the 36-year-old royal and his wife Meghan, Duchess of Sussex, but has rarely seen the pair since they moved to Los Angeles last year.
During an appearance on The Late Late Show With James Corden, Lowe claimed to have just spotted Harry driving his car – and sporting a ponytail.
Lowe, who shot to fame in 1983 as a 19-year-old teen idol in Francis Ford Coppola's The Outsiders, described pulling up in his car near the duke.
The actor told Corden: “I just ran into your countryman, the English treasure Prince Harry, at the stoplight 10 minutes ago.
“He lives about a mile from me. He’s been very reclusive.
“Seeing him in the neighbourhood is like seeing the Loch Ness monster… and I saw him driving his car.
“It looked to me as a casual observer that his hair had grown very long and was pulled back very tightly by what I can only assume was a ponytail.”
Corden replied to Lowe: “I’m certain that isn’t true. I think you didn’t see Prince Harry.”
The actor said he followed the duke back to his home to confirm it was him: “Oh no, it was him because I have to say I followed him to the house to see if the car went in.”
The Sussexes moved to America last March with son Archie after they stepped down as working royals for financial and personal freedom.
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